SQL Server ATN2()

SQL Server ATN2() Function

The SQL Server ATN2() function returns the arctangent of the two specified numbers, which is the angle between the positive x-axis and the point given by the coordinates (y, x). The result is expressed in radians and is useful in trigonometric calculations.

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Syntax

SELECT ATN2(y, x);

The ATN2() function takes two arguments:

• y: The y-coordinate of the point.
• x: The x-coordinate of the point.

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Example SQL Server ATN2() Function Queries

Let's look at some examples of SQL Server ATN2() function queries:

1. Basic ATN2() Example

SELECT ATN2(1, 1) AS result;

This query returns the arctangent of the point (1, 1). The result will be:

result
------
0.7853981633974483

2. ATN2() with Negative Coordinates

SELECT ATN2(-1, -1) AS result;

This query returns the arctangent of the point (-1, -1). The result will be:

result
------
-2.356194490192345

3. ATN2() with a Column

SELECT y_value, x_value, ATN2(y_value, x_value) AS atan2_value
FROM coordinates;

This query returns the arctangent of the points given by the y_value and x_value columns for each record in the coordinates table. The result will show the original coordinates and their corresponding arctangent as atan2_value.

4. ATN2() with a Variable

DECLARE @y FLOAT, @x FLOAT;
SET @y = 1;
SET @x = 0.5;
SELECT ATN2(@y, @x) AS result;

This query uses variables to store the coordinates and then returns their arctangent. The result will be:

result
------
1.1071487177940904

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Full Example

Let's go through a complete example that includes creating a table, inserting data, and using the ATN2() function.

Step 1: Creating a Table

This step involves creating a new table named example_table to store some sample data.

CREATE TABLE example_table (
    id INT PRIMARY KEY,
    y_value FLOAT,
    x_value FLOAT
);

In this example, we create a table named example_table with columns for id, y_value, and x_value.

Step 2: Inserting Data into the Table

This step involves inserting some sample data into the example_table.

INSERT INTO example_table (id, y_value, x_value) VALUES (1, 1, 1);
INSERT INTO example_table (id, y_value, x_value) VALUES (2, -1, -1);
INSERT INTO example_table (id, y_value, x_value) VALUES (3, 1, 0.5);
INSERT INTO example_table (id, y_value, x_value) VALUES (4, 0.5, 1);

Here, we insert data into the example_table.

Step 3: Using the ATN2() Function

This step involves using the ATN2() function to return the arctangent of the points given by the y_value and x_value columns.

SELECT id, y_value, x_value, ATN2(y_value, x_value) AS atan2_value
FROM example_table;

This query retrieves the id, y_value, x_value, and the arctangent of the points for each row in the example_table. The result will be:

id  y_value  x_value  atan2_value
--- -------- -------- ------------
1   1        1        0.7853981633974483
2   -1       -1       -2.356194490192345
3   1        0.5      1.1071487177940904
4   0.5      1        0.4636476090008061

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Conclusion

The SQL Server ATN2() function is a powerful tool for returning the arctangent of two specified numbers, which is the angle between the positive x-axis and the point given by the coordinates (y, x). Understanding how to use the ATN2() function and its syntax is essential for effective trigonometric calculations and data processing in SQL Server.